Double slug tuner



March 29 1955 R NYSWANDER 2,705,307

DOUBLE SLUG TUNER Filed Feb. 1, 1946 FIG.|

FIG. 2

INVENTOR. R. EDSON NYSWANIDER ATTORNEY United States Patent DOUBLE SLUGTUNER R. Edson Nyswander, Denver, Colo., assignor, by mesne assignments,to the United States of America as represented by the Secretaryof theNavy Application February 1, 1946, Serial No. 644,980

4 Claims. (Cl. 333-98) This invention relates to the setting up ofstanding waves in a wave guide and more specifically to the use of adouble slug tuner for the above purpose.

When taking megnatron performance tests, matching loads into a radiofrequency line, or making cold resonance tests it is desirable that atuning mechanism be available which is capable of making independentadjustments of the phase and magnitude of radio frequency standingwaves. Heretofore the tuning devices to accomplish the foregoingpurposes presented difficulties in construction and operation.

A primary object of the present invention is to provide an improvedmethod of forming and varying the phase and magnitude of standing wavesin a wave guide.

Another object of the present invention is to form standing waves in awave guide by providing atuniug mechanism capable of making independentadjustments of the phase and magnitude of the radio frequency standingwaves in the guide.

A further object is to provide a pair of dielectric slugs to be insertedin the wave guide to accomplish the above objects.

A still further object is to provide two slugs of material such asMycalex inserted in a slot cut longitudinally in the broad dimension ofthe radio frequency wave guide for the purposes of the first twoobjects.

A still further object is to provide a mechanism for sliding the twodielectric slugs both with respect to each other and with respect to theguide.

These and other objects will be apparent from the followingspecification when taken in connection with the accompanying drawings,in which:

Fig. 1 is a plan view of one form of the invention; and

Fig. 2 is an end view partially in section of Fig. 1 showing theconstruction thereof in some detail.

The invention broadly consists of a tuning assembly fitted to alongitudinal slot in a wave guide. The tuning assembly contains twodielectric slugs fitting in the .slots of the guide and extending downinto the guide.

The tuning assembly also contains means for moving the slugs verticallyand horizontally in the slots at the same time insuring that each slugextends the same distance into the guide.

The invention lies in the effect that the two dielectric slugs have onthe phase and magnitude of standing waves in the guide. The depth towhich the slugs extend into the guide determines the quantity of radiofrequency energy that will be reflected by them, and thus determines themagnitude of the standing waves set up. The position of the two slugswith respect to the wave guide determines the phase of the standingwaves to be formed and thus allows the maximum and minimum points of thestanding wave pattern to be selected. The spacing between the two slugsdetermines whether the energy reflected by one will be in or out ofphase with that reflected by the other and this in turn will determinethe standing wave ratio.

It is well known in the art that when radio frequency energy strikes anobject of a different dielectric constant than that of the mediumthrough which it is traveling part of the energy will be reflected. Itis the purpose of this invention to introduce into the wave guide twodielectric slugs 4 and of Fig. 1, in such a manner that radio frequencywaves upon entering the guide will strike them and be reflected. Thesereflected waves will combine with the waves entering the guide to set upstanding waves,

2,705,307 Patented Mar. 29, 1955 It has been determined experimentallythat the conditions for maximum standing wave ratio occur when slugs 4and 5 have a longitudinal dimension of and the spacing between thecenters of slugs 4 and 5 is equal to an 4 where:

Ag is the wave length in the guide of the radio frequency energy;

K is the factor by which the wave length is shortened in the dielectricmaterial used in the slug;

n is any integral number.

The longitudinal dimension of the slugs refers to the length of the slugin the direction of propagation of electromagnetic energy within thewave guide.

It is readily apparent that the deeper the slugs extend into the guidethe greater will be the amount of energy reflected and the greater themagnitude of the standing waves.

Referring to Fig. 1 there is shown wave guide 1 with tuning assembly 2mounted thereon. Tuning assembly 2 consists of movable slug carriage 3with Mycalex slugs 4 and 5 mounted thereon held firmly in place by meansof threadably mounted screws 6 and 7 which press firmly against slugs 4and 5 and may be loosened to permit a vertical motion to slugs 4 and 5.Slugs 4 and 5 are held by blocks 8 and 9 with a rod 10 passing: througheach block in such a manner that vertical motion of one slug isimpossible without a corresponding vertical motion of the other. Block 8is rigidly atfixed to rod 10 but block 9 holds rod 10 with a pressed fitin such a manner that block 9 is permitted to slide along rod 10. Slugs4 and 5 are mounted on slug carriage 3 by means of blocks 11 and 12.Block 11 containing slug 4 is fixedly secured to slug carriage 3 butblock 12 containing slug 5 is secured to slug carriage 3 by means ofwing nut 13 which may be loosened to permit motion of block 12 and slug5 along slot 14 of slot carriage 3. Wave guide 1 contains opening 15through which slugs 4 and 5 enter the guide. Slug carriage 3 isconnected by means of screws to blocks 16 and 17 slidably disposed onwave guide 1, being held firmly in place thereby. Slug carriage 3 isthus allowed to slide along longitudinal opening 15 of wave guide 1.

Referring to Fig. 2 the mechanism of both screw 7 for varying slug depthand wing nut 13 for varying slug spacing are shown. Slug depth screw 7is threadably mounted on block 12 and extends therethrough pressingagainst slug 5. Screw 7 is capable of being rotated in such a manner asto hold slug 5 in place or if desirable to permit slug 5 freedom ofmotion in a vertical plane. Slug depth screw 6 operates in exactly thesame manner as slug depth screw 7. Wing nut 13 is threadably mounted onscrew 19 which in turn is threadably mounted on block 12 and passesthrough slot 14. It is readily apparent that by rotation of wing nut 13a means is provided of either holding block 12 firmly in place orleaving it free to move along longitudinal slot 14..

In operation the invention operates to set up standing waves in guide 1.By means of screws 6 and 7, the depth of slugs 4 and 5 can be varied inthe guide and this in turn will vary the magnitude of the standing wavesset up. By means of wing nut 13 the distance between slugs 4 and 5 canbe varied which in turn will vary the standing wave ratio. Slug carriage3 maybe moved along slot 15 and this enables maxima and minima points ofthe standing waves to be positioned at any desirable point of wave guide1.

The invention as disclosed and described applies to setting up standingwaves in a wave guide but the same principle would apply to matching theimpedance of a wave guide to that of a load. Also the use of dielectricor metallic sleeves in a coaxial conductor would in no way deviate fromthe basic principles of the present invention. Metallic rather thandielectric material might be used in the slugs allowing more criticaltuning but having a lower breakdown point.

While a particular embodiment of the present invention has beendisclosed and described it is to be understood that various changes andmodifications may be made therein without departing from the spirit andscope thereof as set forth in the appended claims.

What is claimed is:

1. In combination with a wave guide, one broad wall of which has alongitudinal slot, means for developing standing waves in said waveguide comprising a movable carriage assembly mounted on said wave guide,a pair of dielectric slugs adjustably mounted on said carriage forinsertion into said wave guide through said slot and means to adjust therelative spacing of said slugs along said slot. v

2. A device for forming standing waves in a wave guide, one broad wallof which has a longitudinal slot, comprising a carriage assembly mountedon said wave guide, a pair of rectangular dielectric slugs mounted onsaid carriage extending into said wave guide through said slot, saidcarriage including means for adjustably retaining said slugs in apredetermined spaced relationship with respect to each other and meansfor adjustably retaining said slugs at a predetermined depth ofpenetration in said wave guide.

3. A device for forming standing waves in a wave guide comprising acarriage assembly slidably mounted on said wave guide, a pair ofrectangular dielectric slugs mounted on said carriage extending intosaid wave guide through said slot, said carriage including means foradjustably retaining said slugs in a predetermined spaced relationshipwith respect to each other, and means for adjustably retaining saidslugs at a predetermined depth of penetration in said wave guide, therelative spacing and dimensions of said slugs being such as to form amaximum standing wave ratio in said wave guide.

4. Apparatus as in claim 3 wherein the dimension of said slugs in thedirection of propagation of energy within said wave guide is equal toKhg 4 and the spacing between centers of said slugs is equal to where 1is the wave length of said energy within said wave guide, K is the wavelength modifying factor of the dielectric material of which said slug iscomposed, and n is any integral number.

References Cited in the file of this patent UNITED STATES PATENTS Re.23,131 Webber June 28, 1949 2,238,438 Alford Apr. 15, 1941 2,376,785Krasik May 22, 1945 2,407,267 Ginzton Sept. 10, 1946 2,408,745 EspleyOct. 8, 1946 2,419,208 Frantz Apr. 22, 1947 2,422,160 Woodward June 10,1947 2,423,383 Hershberger July 1, 1947 2,427,100 Kihn Sept. 9, 19472,433,368 Johnson et al. Dec. 30, 1947 2,436,427 Ginzton Feb. 24, 19482,438,913 Hansen Apr. 6, 1948 2,465,719 Fernsler Mar. 29, 1949 2,514,678Southworth July 11, 1950 2,544,842 Lawson Mar. 13, 1951

